Screen for x-ray photography



Patented Nov. 9, 1926.

UNITED STATES IGNATIUS BOND, OF EVANS'ION, ILLINOIS.

SCREEN FOB X-RAY PHOTOGRAPHY.

No Drawing.

My invention relates to improvements in screens for X-ray photography,and it consists in the ingredients hereinafter set forth.

In X-ray photography it is customary to use a fluorescent screen whichmay be placed adjacent to the plate holder when the sensitized plate isbeing exposed. The use of such screens cuts down the time necessary foran exposure. Ordinarily these screens are made of bristol board orcardboard, to which a coating of cementitious material has been appliedwith a coating of a fluorescent salt such as calcium tungstate which isheld in position by means of a cementitious coating,

One disadvantage in the use of a screen of this kind is that thefluorescent coating is apt to be scratched and to be stained badly aftercontinued use, so that eventually the screen becomes useless and isdiscarded.

An object of my invention is to provide a fluorescent screen of the typedescribed which will wear much longer and. at the same time is just asefiective for the purpose.

A further object of my invention is to provide a screen both sides ofwhich may be used, thus giving an additional period of use.

Other objects and advantages will appear in the following specification,and the novel features of the invention will be particularly pointed outin the appended claim.

In carrying out my invention I make use of celluloid. The ordinarymethod of preparing colored sheet celluloid is to incorporate pigmentWith the material when the latter is in a semi-plastic or liquid state,after which the sheets are rolled.

Application. filed July 16, 1924. Serial No. 726,402.

Instead of the ordinary pigment, I make use of fluorescent calciumtungstate. The amount of the salt and of the celluloid is the same, thatis to say, I take for instance five partsby weight of fluorescentcalcium tungstate and live parts by weight of celluloid. These I mixtogether and the subsequent forming of the sheet is done by the ordinaryprocess.

The resultant sheet has the appearance. of an ordinary white celluloidsheet. It has, however, the property of fluorescence. The surface of thesheet is smooth and therein it differs from the ordinary sheet which iscoated with the fluorescent salt. My improved sheet cannot be as easilyscratched as can the ordinary sheet, yet the sheet gives as good resultsas far as cutting down the time necessary for an exposure in an X-raypicture is concerned, as the ordinary sheet. Moreover, when one side hasbeen worn, the sheet may be turned over and the opposite side used,thereby greatly prolonging the life of the sheet. This cannot be donewith the ordinary sheet such as now in use, since the ordinary sheet isonly coated on one side. The fact that my improved composition sheetworks equally well on both sides great- -ly reduces the cost of usingfluorescent screens owing to their longer life.

I claim: a

A fluorescent sheet for use in X-ray photography consisting of acelluloid body portion having smooth surfaces,'said body portion havingincorporated therein fluorescent material so disposed as to render eachface of the sheet equally fluorescent.

IGNATIUS BOND.

